Polymorphism And Photoluminescence In A Naphthalene-Based Ligand, And Its Supramolecular Structures Through Second-Sphere Coordination With The [Cocl4](2-) Anion

A naphthalene-based ligand, N,N,N',N'-tetrabenzyl-naphthalene-1,5-diamine(L1) has been synthesized and crystallized as two polymorphs, alpha and beta. There are no strong hydrogen bonding donors, instead C-H center dot center dot center dot pi interactions play critical roles in the stabilization of the structures of the two polymorphs with different packing motifs. The ligand L1 can be doubly protonated and coordinate with the "second-sphere'' of [CoCl4](2-) using N-H hydrogen bond donors to form two neutral supramolecular complexes [H(2)L1](2+)[CoCl4](2-) (1) and EtOH subset of [H(2)L1](2+)[CoCl4](2-) (2). L1 in 1 and 2 adopts the arrangement manner of stable polymorph alpha. The [CoCl4](2-) anions are connected with L1 through N-H center dot center dot center dot Cl interactions, meanwhile, the anion [CoCl4](2-) acting as an "off-on'' switching template controls the photoluminescence.